PCB Repair Logs Xevios
Xevios is a bootleg of Xevious
Bought this board ages ago from E-bay which is a bootleg version of Xevious. I got the game working ok but the sound wouldnt work.
I replaced the MB3730 amp booted her up but it would give me some ram error and the screen would be full of static and wavyness. If you removed the 12 volt line it would be fine. I thought this would be a simple fix but how wrong was I.
This game didnt really interest me so i got sick of wasting time on it and threw it on the "I'll get to it some day" pile.
Working on Galaxians and my retro fit amp I stumbled on the same problem when I removed a big 2200uf cap that ran from the 12 volt line to ground. Only reason I removed it was I noticed more modern PCBs used a 470uf cap with this amp and wanted to see what the difference was if any.
I managed to recreate the exact ripple as Xevios had. Had a brain storm so after I finished my work on Galaxians I pulled out Xevious which by this time I had pulled parts off it. I managed to find all the parts ran a 470uf cap from the 12volt line to ground and hey presto working board with sound.
So the cap running from the 12 volt line to ground is used to get rid of the ripple. I'm sure somebody non backyarder can explain it better than me.
Lesson learned. There is a small fault I will get to one day where if you turn the voltage up to 5 volts the sound gets all messed up and random. Running the board at 4.5 volts it runs fine.
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